Abstract: Relations between AI outcome and some metabolic parameters (Urea, Ammonia, Glucose, Cholesterol, Triglycerides, NEFA, -OHT and Progesterone) were assessed in dairy cows. Significant differences were present most of all in the 35-140 days postpartum period. The concentration of haematic Ammonia seem to be a very important factor conditioning AI outcome; both as hepatic functionality index and for toxic effects on neuroendocrine control mechanisms, including reproductive function.